If you know the circumference of a circle, what is the r?

Divide Circumference by pi (3.1415) to get diameter. Divide diameter by 2 to get radius.

if you are given any one of the following, radius, diameter, circumference, or area. You can find all of the others. Memorize the formulas for Circumference (Pi*diameter) and Area (Pi * Radius squared) and the fact that radius * 2 = diameter, and you can do all of them. so:

Circumference = 2 Pi R

To find R you divide the circumference by (2 Pi)

R = Circumference /(2*3.14159)

Jul 8th, 2014

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